Which of the following compounds is a tertiary amine?

• A. $\mathrm{ethylamine}$
• B. $N,N,\mathrm{dimethylethylamine}$
• C. $\mathrm{aniline}$
• D. $\mathrm{diethylamine}$

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the definition of a tertiary amine. A tertiary amine is a nitrogen atom bonded to three alkyl or aryl groups, with no hydrogen atoms attached directly to the nitrogen.
2. Step 2: Analyze each compound's structure to determine the number of alkyl or aryl groups attached to the nitrogen atom.
3. Step 3: For ethylamine, identify that the nitrogen is bonded to one ethyl group and two hydrogens, making it a primary amine.
4. Step 4: For diethylamine, note that the nitrogen is bonded to two ethyl groups and one hydrogen, classifying it as a secondary amine.
5. Step 5: For N,N-dimethylethylamine, observe that the nitrogen is bonded to one ethyl group and two methyl groups, with no hydrogens attached, making it a tertiary amine.